Means for varying the pitch of propeller blades, especially aircraft propeller blades



MEANS FOR VARYING THE PITCH OF PROPELLER BLADES, ESPECIALLY AIRCRAFT PROPELLER BLADES June ,1 A. G. FORSYTH El AL 2,161,917

Filed Nov. 24, 1957 11 Shets-Sheet 1 R Q Q June 1939- A G. FORSYTH ET AL 2,151,917

PROPELILYER BLADES.

LER BLADES ll Sheets-Sheet ,2

MEANS FOR VARY ING THE PITCH 0F ESPECIALLY AIRCRAFT PROPEL Filed Nov. 24, 1937 Dre/2 fo Aim/wag;

June 13, 1939. A. G. FORSYTH ET AL 2,

MEANS FOR VARYING THE PITCH OF PROPELLER BLADES,

ESPECIALLY AIRCRAFT PROPELLER BLADES Filed NOV. 24, 1937 ll Sheets-Sheet 3 [hue/7 fora MQQM June 13, 1939. A. e. FORSYTH ET AL 2,161,917

MEANS FOR VARYING THE PITCH OF PROPELLER BLADES,

ESPECIALLY AIRCRAFT PROPELLER BLADES Filed NOV. 24, 1957 11 Sheets-Sheet 4 Im'eh fora: Archive/d 6/1704) E Jyfb, a George me-s- JW/M- June 1939- A. s. FORSYTH ET AL 2,161,917:

MEANS FOR VARYING THE PITCH OF PROPEYiLER BLADES, ESPECIALLY AIRCRAFT PROPELLER BLADES Filed NOV. 24, 1937 ll Sheets-Sheet 5 fm cnfons June 13, 1939. G, FORSYTH r AL 2,161,917

MEANS FOR VARYING THE PITCH OF PROPELLER BLADES. ESPECIALLY AIRCRAFT PROPELLIER BLADES Filed Nov. 24, 1937 ll Sheets-Sheet 7 MRQW x I June 1939- A. G. FORSYTH ETAL 12,161,917

MEANS FOR YARYING THE PITCH OF PROPELLEJR BLADES ESPECIALLY AIRCRAFT PROPELLER BLADES Filed Nov. 24, 1957 ll Sheets-Sheet 8 [m ew fora A .47 fo/weya June 13, 1939. A. G. FORSYT H ET AL F PROPELLER BLADES MEANS FdR VARYING THE PITCH O ESPECIALLY AIRCRAFT PROPELLER BLADES Filed Nov. 24, 1957 ll Sheets-Sheet 9 m QQM J1me 1939- A. ('5. FORSYTH ET AL MEANS FOR VARYING THE PITCH OF PROPELLER BLADES,

ESPECIALLY AIRCRAFT PROPELLER BLADES Filed NOV. 24, 1937 11 Sheets-Sheet l0 June 13, 1939. A. G. FORSYTH ET AL 2,161,917

MEANS FOR VARYING THE PITCH OF PROPELLER BLADES.

ESPECIALLY AIRCRAFT PROPELLER BLADES Filed Nov. 24,1957 ll Sheets-Sheet'll QQW Patented June 13, 1939 MEANSFOR VARYING THE PITCH OF PRO- PELLER BLADES, ESPECIALLY AIRCRAFT PROPELLER BLADES Archibald Graham Forsyth and George James Smith-Port, Cheam, England, assignors to The Fairey Aviation Company Limited, Hayes, ltIiddlescx, England Application November 24,

1937, Serial No. 176,372

In Great Britain May 24, 1937 3 Claims. (01. 170-163) This invention relates to means for varying the pitch of propeller blades, and especially of aircraft propeller blades, and has for its object, to provide lighter and smaller mechanism for this purpose than has usually been employed in the past.

To this end and in accordance with the present invention, avariable pitch propeller has blades with means for turning them through 360. Preferably the pitch of the propeller blades is varied by a reversible fluid-operated motor of the continuously rotatable type. Preferably also, oil is supplied to the motor, by a pump driven from, for example, an aircraft engine, and it may be supplied through a two-way valvecontrolled by a governor driven by said engine, the arrangement being such that admission of oil through one way of the two-way valve drives the fluid operated motor in the one direction and admission of oil through the other way of the two-way valve drives the motor in the other direction. In some cases, however, the two-way valve may be controlled manually, e. g., by the pilot of an aircraft. If desired means may be employed for imposing maximum and minimum pitch values and those means may be such that these values may be adjusted. When the invention is applied to aircraft propellers, the fluid operated motor may be mounted in front of the hub of the pro- 0 peller in which case the oil conduits for the motor may be accommodated within the propeller shaft. r

The invention is illustrated by the accompanying drawings wherein Figure 1 is a longitudinal section of the nose of the propeller hub taken on the line Figure 10,, parts being broken away or omitted for the sake of clearness; Figure 2 is a cross-section on the line 22, Figure '9; Figure 3 is a face view of a detail; Figure 4 is a section on the line 44, Figure 9; Figure 5 is a section on the line 5-5, Figure 4; Figure 6 is a sectional view of a detail; Figure '7 is a diagrammatic end view of a detailfitting which provides shaft bearings; Figure 8 is a section on the line 5 8-8, Figure 7; Figure 9 is a sectional front view v of part of the hub portion of a variable pitch propeller arranged in accordance with one form of this invention, the section being taken on the 0 line 99, Fig. 4; Figure 10 is a front view thereof 4 with the nose proper removed; Figure 11 is a sectional front view on the line Figure 1, parts being omitted from Figures 10 and 11 for the sake of clearness; Figure 12 is a frag- 'mentary plan view; Figure 13 is a longitudinal section of a unit for controlling the flow of oil 'ble motor herein diagrammatically illustrated,

under pressure to the fluid operated motor; Figures 14, 15 and 16 are sections on the lines |4--|4, |5-I 5 and Iii-l6, respectively, of Figure" 13; Figure 17 is a section on'the line ll, ll, Figure 15; Figure 18 is a diagram, as viewed in the axial di- C rection, of modified gear for transmitting power from the fluid operated motor to the propeller blades andFigure 19 is a sectional side view thereof.

As shown in Figure 9, the root 4| of each blade is screwed into a socket 42 and locked by a pin 43. The outer end of the socket 42 is surrounded by a bush 44 revoluble in a socket 45 screwed into the hub body 46, a worm wheel 41 is screwed on to the inner-end of said socket 42 and a roller .16

-or ball race 48 is interposed between the inner end of the socket 45 and the worm wheel 41 to take the centrifugal loading from the blade root 4|, through the socket 42, the worm wheel 41, the roler race 48 and socket 45 back to the hub body 46. The worm wheel 41 is locked to thesocket 42 by means of a plate 49 (Figure 3); splined on the inner end of the socket 42 and connected with the worm wheel 41 by dowel-pins 50 and screws 5|.- 52 is a second bearing to take the rotational movement of the blade root 4|.

Meshing with the worm wheel'41 is'a worm 53 carried in the hub body 46 by thrust bearings 54, 54 (Fig. 2) which take the, end thrust in both directions and thus definitely locate saidworm s30 53; hence the worm drive to the blade is irreversible, that is to say although it can be operated to turn a blade in either direction forces acting on the blade cannot drive the worm 53. 55 is a bevel wheel on the shaft of the worm 53 and the bevel wheefs 55 appertaining to the several blades of the propeller mesh with bevel wheels such as 56 carried by shafts, such as 51, Figure 6, having at their opposite ends skew gear wheels, such as 58 mounted to rotate in sleeves 59. As indicated in Figures 7 and 8 the sleeves 59 form part of a fitting 60 and are disposed so that the axes of the shaftssuch as5l are substantially convergent and so that the skew gear wheels 58 may. mesh with a common worm 6| splined on the shaft 62 of the fluid-operated motor indicated generally at 63, Figure 1. The fluid-operated motor 63 may be of any suitable reversible type such as the-continuously rotatable fluid operated reversihence rotation thereof in either direction will drive the worm 6|, skew gear wheels 58, shafts 5i, bevel wheels 56, 55,.worm's 53, and worm wheels.

41 to rotate the-propeller blades in either direction and said blades willbe locked in their adjusted positions when the motor '68 is stopped; further the mechanism provided is adapted to rotate said blades through 360.

Oil under pressure is supplied to the motor 68 from the-oil supply 01 the aircraft-engine (or from a constant speed unit to be mentioned hereinafter) by way of pipes 68 and 65, Figures 4, 5 and 12 which, by means of a two way cock may be caused to serve either as inlet or exhaust pipes, respectively, or conversely. The pipes 68 and 66 are connected with the housing 66 which is arranged to be fixed on the forward end of the crankcase of the aircraft engine and as shown in Figure 12 they do not lie on the same transverse plane. Assuming to be the oil inlet pipe for the time being, oil passes therefrom to a groove 61 in the housing 86, along a twin passage 88 to a passage 68 (Figure 1) and thence through an aperture 18, Figures 1 and 11, to passages 1i and 12 to a port 18 to the motor 88. The exhaust from the motor 88 is by way of a port 18 (Figures 1 and 11), through passages 16 and 16, an aperture 11, Figure 10, corresponding with'the' aperture 18, a twin passage 18, Figure 4, corresponding with the passage 68 and a groove 18 in the housing 66 to the pipe 86 and thence back to the engine sump or the oil tank. The true positions of the passages 88 and 18 are shown in Figure 9.

Oil leakage from the grooves 61 'and 18 is con-o a trolled by three piston rings 88, Figures! and 1,

and an oil seal M is provided to prevent oil from leaking to the outside of the housing 66, whilst drains, such as 82, are provided to carry excess oil back into the engine crank case.

Although the mechanism of this invention, as,

' thus far described, is adapted to turn the propeller blades through 360", it is desirable, in some circumstances to arrange, that the pitch of said blades shall have predetermined .maximum and minimum values, 1. e., that the blades cannot be set at more than a predeterminedpitch or at less than a predetermined pitch, but can be set v at any intermediate pitch. To enable this to be done the pipe and passage connections between the pipes 68 and 86 include two valves such as 88 Figure 1, the angular situations of whic are indicated by the valve housings 88 and 86 in Fig ure 11. The spindles of the worms 68 at these angular situations have screw threaded extensions, as shown at 88, Figure 1, and on each extension 88 is a nut 81, the peripheryof which .is serrated as shown in Figure 10.' A cover 88, closing an aperture inthe adjacent part of the feather 88 which is received between two adjacent teeth of the nut 81; thus preventing it from turning. Hence when the worms 58 are revolved, the nuts, such as 81, on their extensions such as 86, are caused to travel along said extensions. It will be observed, Figure 10, that the serrations are such that when a space betweentwo teeth of a nut 81 is at the top, the end of a tooth is at the v bottom, of the vertical centre line. Each valve, such as 88,'has a stem, such as 88, Figure 1, projecting radially outwards to such an extent .that its free 'end overlaps the teeth of the nut 81 when the valve is on its seating; Figure 1 shows the position of the parts when the valve 83 has just closed, the motor 88 has stopped through lack of circulation of oil, and revolution of the worms 88 has ceased, i. e., the propeller blades have been set to a predetermined limit pitch value, in this instance the minimum value. It new oil under pressure be admitted through the pipe .1 the valve 88 shown in Figure 1 will be blown ofl pitch to cease.

nose of the propeller; is furnished with a key or 88 with a tooth on the corresponding nut 81,

until, when the pitch of the propeller blades has been varied to such an extent that the maximum pitch value has been attained, said nut will have been caused to travel along its appertaining threaded spindle extension 86 to such an extent that the end of the valve stem 88 will become disengaged from a tooth of said nut and the .valve, which, for the time being is the outlet 'valve,

will close, its stem 88 rising on the outside of the nut 81, and once again lack of oil circulation will cause the motor 63 to stopand the variation of By removing the covers 88 access may be had to the nuts 81 and by turning said nuts and replacing the covers. 88 with their keys 88 engaged between different teeth, the maximum and minimum pitch'values which the propeller blades are to be allowed to attain may be varied. Actually, an angular adjustment of a nut 81 corresponding with one tooth will alter the predetermined pitch value by approximately this can be controlled by arranging suitable screw threads and serrated nuts to give any desired setting.

Figures 13, 14, 15, 16 and 1.7 illustrate a unit for controlling the flow of oil to the fluid operated motor 83. This device comprises a-pump constituted by interengaging gear wheels 8I, 82, the gear wheel 8| being mounted on a hollow spindle 88 and the gear wheel 82 being mounted on a hollow spindle 84, -which extends upwardly through the unit. Oil is admitted to the unit through a passage and passes down through the hollow spindle 88 to twin passages 86, 81 (Figure 16) which communicate with twin pump inlet ports 88, 88 (best seen in Figure 17). Twin pump outlet ports 108, Ml communicate on the one hand, by a passage I82 with an annular groove I 83 (Figures 13 and- 14) formed around the spindle 84, and, on the other hand, by a passage I08 through a relief valve I05 (Figure 1.4;) with an oil outlet to the sump.

As shown, the inlet port 88 and the outlet port I88 are closed by plugs I86, I86, but if desired, these ports may be left open and the inlet port 88 and the outlet port I8I may be closed instead by plugs I86, I86. In this way, the pump may be arranged to deliver oil to the passage I82 irrespective of the sense of rotation of said pump. The annular groove I83 communicates by apertures such as I81 in the spindle 88, with an annular space I88 between a double piston valve I88 and said spindle 84. Said piston valve I88 is sidable axially of the spindle 88 under centrifugal control (as will be explained hereinafter) and, in its mid position it closes two ports I I0, I I I through which oil may be admitted to the pipes 64, 65 respectively leading to the fluid operated motor 63. 'Apertures such as II2 are formed in the upper part of the piston valve I88 and the hollow spindle 88 communicates at its lower end with the sump by apertures such as H3 (Figure 13) for a purpose to be explained 10 hereinafter.

Operation H5, "5, are pivotally mounted on lugs III, III. a pinion Ill meshing with a gear wheel III Noses H1, H1 of the balance weights "5,1",

bear on the underside of a ballrace 'I ll mounted on an extension H9 ofthe piston valve I.

The spindle M is arranged to be driven from the aircraft engine through splines formed on the lower end thereof. A spring III is located between a collar I23, secured to the extension ll! of the valve Hi5, and a member III which is slidably mounted upon a rod carried by the collar I23. The member I is formed with rack teeth which mesh with a pinion I which pinion may be rotated in one direction or the other by a control in the cockpit of the aircraft so as to cause axial movement of the member iii and consequent variation of the pressure exerted by the spring I22.

In operation, oil enters the unit (from the ordinary oil pressure systemof the engine) by the passage 95 and passes down the hollow spindle I3, throughthe passage 01 to the pump inlet ll. The pump, rotated by the hollow spindle 8| (which is rotated by the aircraft engine through splines at its lower end as described above) delivers oil through the outlet IOI to the passage ll! whence it passes to the annularspace 103 and thence through the apertures III to the annular'space I" surrounding the. piston valve I". If now the engine speed is such that the piston valve closes the ports II and III, the oil pressure built up in the passage III will open the relief valved and allow the oil to flow back to the sump. Suppose, however, the engine speed is such that the piston valve III. is lifted by the governor balance weights I I5, I I! to open the ports I I II and Oil under pressure'will now flow from the annular space I08 through the port 0 to the pipe 64 which leads to the fluid operated motor through valve 83 so long as said valve is kept open by the nut ll (seeFig. 9), and said motor .will be rotated to turn gears I and 55 and worm port ill to the pipe ll leading to the fluid operated motor 83. The motor will then be r0-, tated to decrease the pitch of the blades. Oil returns by the pipe '4 and passes through the port III and'apertures' II! to the inside of the piston valve l I! whence it flows down the hollow-spindle -94 and returns to the sump through the apertures Ill.

As shown in Figures 18 and 19, the shaft '2 of the fluid operated motor It carries a skew gear wheel I24 meshing with a corresponding skew gear wheel I! on a shaft III on the other end of which is a skew gear wheel II| driving a skew gear wheel III ona-shaft III on whichisthe propeller is not revolving.

with which also mesh pinions such as III on shafts such as m on which the worms II are mounted.

The arrangement in accordance with thisinvention is such that by hydraulically fil rs-ted means the pitch of the propeller bladescan be varied and if desired they may be feathered. i. e., set substantially in a fore and aft plane so that they presentthe minimum resistance if The unit as a whole is adapted for use with different types or powers of engines and may be arranged so as to be interchangeable.

We claim: 1. A variable pitch propeller comprising a hub. a reversible fluid operated motor mmmted on said hub, propeller blades having roots rotatable in said hub, means including shafts driven by said motor in opposite directions for rotating said,

pump driven by the aircraft engine and including 'a manually adjustable valve responsive to engine speed for regulating the pump outlet within predetermined manually. adjusted limits and apair of valves controlling the'flow of oil to and from the motor for rotating said motor in'opposite directions, screw threaded extensions on two of said shafts and nuts on said extensions for acting on said valves, keys flxed relatively to said nuts, each of said nuts being formed with an odd number of teeth between any two of which one of said keys may be engaged, that tooth which is diametricallyopposite to the key being adapted to cooperate with the stem of one of said valves.

2. A variable pitch propeller comprising a hub. a reversible fluid operated motor mounted on said hub, propeller blades having roots rotatable in said hub, shafts driven by saidmotor in opposite directions for rotating 'said blade .roots, a fluid system conveying oil to and from said motor, said system including oil pump means driven by the aircraft engine for supplying oil to said fluid operated motor and including a manually adjustable valve responsive to engine speed for regulating the pump output within predetermined manually adjusted limits and a pair'of valves controlling the flow of supplied ofl to and from said motor for rotating said motor in opposite directions, screw threaded extensions on two of said shafts. and nuts on said extensions for acting on said valves, removable keys flxed relatively to said nuts, each of said nuts being formed with an odd number of teeth between any two of which one of said keys may-be engaged, that tooth which is diametrically opposite to the key being adapted'to' cooperate with the stern'of one of said valves. p v

a. a variable pitch propeller as claimed in claim 2 wherein each keyforms part of a removable cover. 7

ARCHJBALD 'GRAHAI GEORGE JANE slim-rm. 

